The whole point of autofill was to reduce queue times. I am in no means a great player, but I am not as bad as the monkeys that fill my primary role as I am autofilled into something else. It's like Riot purposely tries to get underskilled players in that primary position. I would honestly wait a whole 30 minutes in queue than get autofilled into a game destined to lose from champ select. This is especially true when your flex rank is much lower than your solo/duo rank, and you're just trying to rank up flex.